Fuel compositions for vehicles are continually being improved to enhance various properties of the fuels in order to accommodate their use in newer, more advanced engines including direct injection gasoline engines. Accordingly, fuel compositions typically include additives that are directed to certain properties that require improvement. For example, friction modifiers, such as fatty acid amides, are added to fuel to reduce friction and wear in the fuel delivery systems of an engine. However, certain fatty amides may be unstable in additive packages for fuels at low storage temperatures and the performance of such fatty acid amides is often less than desirable. Fuel additives may be passed into the oil sump during engine operation, so that a fuel additive that is also beneficial to the engine lubricant is desirable. While such additives may be beneficially added to the lubricant rather than the fuel, such additive are not effective for improving wear in fuel delivery systems. Also, such additives, when added to the fuel, rather than the lubricant, may reduce friction and wear in the piston ring zone of the engine and thus improve fuel economy. Accordingly, it is beneficial to include additives in fuels to provide both improved fuel delivery system wear protection as well as improved fuel economy.
Partial esters of fatty acid and polyhydroxy alcohols such as glycerol monooleate (GMO) are known as friction modifiers for lubricant compositions. Likewise diethanolamine fatty amides are also well known friction modifiers. While GMO and fatty amide friction modifiers may improve fuel economy when added to a lubricant, GMO and certain diethanolamine fatty amides may be unstable in additive packages for fuels or may cause an increase in intake valve deposits in gasoline engines. Furthermore, fuel economy improvement may be less than desirable when using GMO or certain fatty amides in fuel compositions. Accordingly, GMO and fatty amide friction modifiers cannot be beneficially added to a fuel composition to improve the wear protection of the fuel delivery system without harmful and undesirable side effects.
Fatty amine ethoxylates are also known as fuel additives that may reduce fuel consumption. However, such fatty amine ethoxylates are typically derived from natural sources and thus may vary by region and over time. In addition, some fatty amine ethoxylates have a high freezing points or are solids at room temperature and may require heating or the use of a solvent for storage and handling. Lastly, fatty amine ethoxylates typically have poor low temperature compatibility with fuel compositions.
Certain etheramine polyalkoxylates were believed to be useful as anti-corrosion additives in gasoline fuels. However, such compounds perform poorly with regard to corrosion in a NACE TM0172-2001 corrosion test and may dramatically increase the amount of intake valve deposits in an engine.
Many other friction modifiers have been tried, however there remains a need for a friction modifier that enables a fuel additive packages containing the friction modifier to remain fluid at low temperatures, that is resistant to hydrolysis, that may be readily formulated into a fuel additive packages, that offers good fuel economy benefits, and that provides wear protection to fuel delivery systems, among others characteristics. Accordingly, there continues to be a need for a fuel additive that is cost effective to manufacture and improves multiple characteristics of a fuel.
In accordance with the disclosure, exemplary embodiments provide a method for improving fuel economy in an engine. The method includes providing a fuel composition to an engine, wherein the fuel composition comprises gasoline and from about 10 to about 750 ppm by weight based on a total weight of the fuel composition of a fuel stable additive of the formula
wherein R1 comprises a saturated hydrocarbyl group having from 6 to 30 carbon atoms, R2 is an alkylene, polyalkylene, alkoxyalkylene, or polyalkoxyalkylene group containing from 2 to 25 carbon atoms, R3 is an alkyl group containing from 2 to 5 carbon atoms, R4 is a linear alkyl group containing 2 to 3 carbon atoms, and x is an integer selected from 0 and 1, and combusting the fuel composition in the engine.
In another embodiment, there is provided a method for improving the fuel economy in an engine. The method includes providing to the engine a fuel composition, wherein the fuel composition comprises gasoline and from about 10 to about 750 ppm by weight based on the total weight of the fuel composition of a fuel stable additive that is a polyhydroxyalkyl ether amine, wherein the polyhydroxyalkyl ether amine contains one or more tertiary nitrogen atoms and is devoid of primary and secondary nitrogen atoms, and combusting the fuel composition in the engine.
A further embodiment provides a fuel composition that includes gasoline and from about 10 to about 750 ppm by weight based on the total weight of the fuel composition of an additive of the formula
wherein R1 comprises a saturated hydrocarbyl group having from 6 to 30 carbon atoms, R2 is a linear alkylene group containing from 2 to 25 carbon atoms, R3 is an alkyl group containing from 2 to 5 carbon atoms, R4 is a linear alkyl group containing 2 to 3 carbon atoms, and x is an integer selected from 0 and 1.
An advantage of the methods described herein is that the additive for the fuel composition may not only improve the friction or wear properties of the fuel, but the additive may also be effective to improve fuel economy without detrimentally affecting the low temperature stability of a fuel additive package containing the additive component.
In one embodiment, the additive is derived from a hydrocarbyl substituted ether amine that is reacted with an epoxide. In another embodiment, the hydrocarbyl group of the hydrocarbyl substituted ether amine contains from 6 to 30 carbon atoms.
In one embodiment, the hydrocarbyl ether amine is a compound of the formula
wherein R1 comprises a saturated hydrocarbyl group having from 6 to 30 carbon atoms, R2 is an alkylene, polyalkylene, alkoxyalkylene, or polyalkoxyalkylene group containing from 2 to 25 carbon atoms, R3 is an alkyl group containing from 2 to 5 carbon atoms, R4 is a linear alkyl group containing 2 to 3 carbon atoms, and x is an integer selected from 0 and 1.
In a further embodiment, the fuel composition contains from about 10 to about 750 ppm by weight, such as from 40 to about 500 ppm by weight, or from 50 to about 250 ppm by weight of the polyhydroxyalkyl ether amine based on a total weight of the fuel composition.
Additional embodiments and advantages of the disclosure will be set forth in part in the detailed description which follows, and/or can be learned by practice of the disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.